The International Atomic Energy Agency has initiated a Coordinated Research Project (CRP) for the development of nuclear techniques for landmine detection. Out of the fourteen institutes participating in the CRP, twelve are working on neutron-based techniques. Small isotope neutron sources and D-T neutron generators have been used by the researchers. The techniques used include neutron scattering by explosives as well as gamma spectroscopy following the interaction of neutrons with explosives. Neutrons are readily thermalized by hydrogen in explosives and backscattered. Cape Town University, South Africa, and Delft University, Netherlands, have developed instruments based on this principle. Both are portable units and laboratory tests prove their capability to detect dummy landmines (100 g explosive simulant) buried 3-6 cm below dry soil. Further improvements are in progress. Another device, PELAN, developed by the Western Kentucky University, U.S. is based on pulsed fast and thermal neutron activation and has reached a fairly advanced stage of development. The equipment was tested with real mines in a test field in Croatia. In this first series of tests, PELAN could detect antitank mines (5.6 kg explosive) buried 7.5 cm below soil, and antipersonnel mines (200 g explosive) buried 5 cm below soil. More field tests and methods for improving performance are being pursued. The research groups are investigating different facets of the problem such as detector development, Monte Carlo calculations, spectrum unfolding, detector shielding and data analysis.
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